In the middle of a day golf starts to sound terrific (7)
I believe the answer is:
amongst
'in the middle of' is the definition.
(I've seen this before)
'a day golf starts to sound terrific' is the wordplay.
'day' becomes 'mon' (abbreviation for Monday).
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'starts to' indicates taking the first letters.
The initial letters of 'sound terrific' is 'st'.
'a'+'mon'+'g'+'st'='AMONGST'
(Other definitions for amongst that I've seen before include "Having been absorbed, perhaps" , "Famous novel by John McGahern: '... Women'" , "Within the group of" , "Surrounded by" , "In the midst of" .)